Our coral work with Montipora verrucosa will focus on five questions: (1) duration of alloimmune memory, (2) timing of immune sensitization, (3) immunogenetic library size or variation in immunocompetence of given clones, (4) testing of hypothesis that specific first-phase sensitization is followed by non-specific second-phase cytotoxicity and (5) identification of xenocytotoxic macromolecule found in Fungi mucus. The sea star (Dermasterias) work will emphasize (1) cellular identification of immunocytes and their tissue sources; (2) search for immunoglobulins in plasma of immunized (TNP-ficoll and streptococcal vaccine) animals by radioimmunoassay; (3) search for immunoglobulin-like receptors on the surfaces of lymphocyte-like cells of this species by electron microscopy. Two projects will be extended with genetically-defined mice. The first is to determine the extent and effects of polymorphism of histocompatibility loci located on the X and Y chromosomes. The second project will characterize the genetic control of the immune response to TNP-MSA. Further experiments will determine (1) the possible effects of Ir-6 on TNP-antibody heterogeneity as a function of polyclonality/idiotypy in high vs. low responders using isoelectric focusing; (2) the T-cell vs. B-cell basis for the genetic control of this immune response and (3) the genetic basis for low responsiveness in F1 hybrids.